<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>鼠标测试</title>
        <link rel="stylesheet" type="text/css" href="practice9_3.css" />
    </head>
    <body>
        <h1>把鼠标移到此处试试</h1>
    </body>
    
</html>